Oestrogen receptor, progesterone receptor and HER2 results depend on pre-analytical handling. Long cold ischaemia time before fixation and under- or over-fixation can both give false-negative results, and a false negative may deny a patient endocrine or HER2-directed therapy.
The widely used standard is prompt immersion in 10% neutral buffered formalin with a fixation time of about 6 to 72 hours. Recording these times on the request form and in the report lets a reader judge an unexpected negative.
- Ask theatres and clinics to record the time the specimen left the patient and the time it entered formalin.
- Use 10% neutral buffered formalin and a specimen-to-fixative volume ratio of at least 1 to 10.
- Record total fixation time in the report for every breast biomarker test.
- Repeat testing on another block or specimen when a negative result does not fit the morphology.
Why it matters
A pre-analytical error can deny a patient a treatment the tumour would have responded to.
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